1. Field of the Invention
The present invention relates to an original conveying apparatus, and more particularly, to an original conveying apparatus wherein originals separated from an original stack one by one from the uppermost one are held and conveyed by a conveying and holding means in page sequence, and, in particular, the present invention relates to an original conveying apparatus which can be mounted on an overhead projector (OHP) for projecting an image of an original onto a screen.
2. Related Background Art
An example of a conventional original conveying apparatus which can be mounted on an overhead projector (OHP) will be explained with reference to FIG. 7. A convey film 51 and a hold-down film 52 serve to hold and pinch an original therebetween, and these films are elongated transparent films each having a width greater than a width of the original.
The convey film 51 on which the original rests serves to move the original to the left as the film is shifted in a film winding direction. The hold-down film 52 serves to hold down an upper surface of the original against the convey film 51 to prevent the original from curling and damaging. Further, frame marks are formed on an edge portion of the convey film 51 at a predetermined interval. By detecting such frame marks by a frame detection sensor 53, a desired original is positioned on an exposure portion.
One end of the elongated convey film 51 and one end of the elongated hold-down film 52 are attached to a first take-up means 54 so that these films can be wound around the first take-Up means. As shown in FIG. 7, the first take-up means is arranged at the right of a reading area of the exposure portion 202 of an OHP apparatus 201 and comprises a first convey roll 54a on which the convey film 51 is wound and a first hold-down roll 54b on which the hold-down film 52 is wound. These rolls are rotatably mounted between front and rear frames. Incidentally, as shown in FIG. 7, a positional relation between the first convey roll 54a and the first hold-down roll 54b is selected so that the first convey roll 54a is disposed below the first hold-down roll 54b.
The other ends of the elongated convey film 51 and hold-down film 52 are attached to a second take-up means 55 so that these films can be wound around the second take-up means. As shown in FIG. 7, the second take-up means is arranged at the left of the reading area of the exposure portion 202 of the OHP apparatus 201 and comprises a second convey roll 55a on which the convey film 51 is wound and a second hold-down roll 55b on which the hold-down film 52 is wound. These rolls are rotatably mounted between the front and rear frames.
A tensioning means serves to tension the convey film 51 and the hold-down film 52 so that these films pinching the original therebetween are closely contacted with the exposure portion (platen glass) 202 of the OHP apparatus 201, and comprises a pair of right side rollers 56a, 56b arranged at the right of the reading area of the exposure portion 202 and a left side roller 56c arranged at the left of the reading area of the exposure portion 202. Further, as shown in FIG. 7, the convey film 51 and the hold-down film 52 pass above the right side lower roller 56a and below the left side roller 56c so that these rollers are tensioned and are closely contacted with the exposure portion 202. Further, the right side upper roller 56b is also rotatably mounted on the front and rear frames and is biased by a spring and the like (not shown) to be urged against the right side lower roller 56a. By passing the convey film 51 and the hold-down film 52 between the pair of right side rollers 56a, 56 b, these films 51, 52 are closely contacted with each other.
Further, a remote control receiving portion is provided on an operation panel 57 of the original conveying apparatus so that left and right motors (not shown) can be operated under the remote control. As shown in FIG. 7, a supply tray 58a from which the original is supplied and-a movable tray 58b are attached in the proximity of the first take-up means 54, and the movable tray 58b can be retracted as the right side upper roller 56b is rocked. Further, an original detection sensor (not shown) of reflection type for detecting the presence/absence of the original is associated with the supply tray 58a.
Further, as shown in FIG. 7, detecting elements of the frame detection 1 sensor 53 are disposed between the pair of right side rollers 56a, 56b and the first convey roll 54a with the interposition of the convey film 51. The frame detection sensor 53 may be of a permeable type which can detect the light-blocking frame marks formed on the edge portion of the convey film 51. Further, original guides 59a, 59b are fixed to front and rear side plates (not shown) and serve to guide the original between the convey film 51 and the hold-down film 52 when the original wound around the first convey roll 54a or the second convey roll 55a is supplied and to wind the original around the first convey roll 54a or the second convey roll 55a without striking the original against such roll when the original is wound around the first convey roll 54a or the second convey roll 55a together with the convey film 51.
However, in the above-mentioned conventional original conveying apparatus, since, after the originals are set on the supply tray 58a one by one and are wound around the second convey roll 55a together with the convey film 51, the preparation (setting) is effected by winding the convey film 51 with the originals around the first convey roll 54a and then the presentation is started, the following problems arose:
(1) Since the originals are set on the supply tray 58a one by one, if the number of the originals is great, it takes a long time,for setting the originals; PA1 (2) Since the presentation cannot be started until the originals are firstly wound around the second convey roll 55a and then are wound around the first convey roll 54a again, the preparation is troublesome; and PA1 (3) When the originals are desired to be changed after the originals were set or when the page sequence of the originals is desired to be changed or when additional original(s) are desired to be added between the existing originals, since the originals already set must be collected, it takes a long time for satisfying the request.